Paying for your everyday purchases with rewards credit cards is a great way to earn some extra money, but using these cards isn't always straightforward. The financial blog Wealth Pilgrim points out five gimmicks and gotchas to be wary of.

Each rewards program has different restrictions that can trip you up and keep you from getting the most out of your card. (And since we tend to spend more when we think we're getting rewards back, it's best to do all we can to make sure we get the maximum reward). For example, advance reward sign-ups with rotating reward categories require you to sign up by a specific date to get the maximum rewards rate. You miss that deadline, and you're stuck with the base rewards rate.

You should also be aware of minimum spending thresholds, which could affect the rate you earn:

The Chase Freedom consistently offers 1% back on all non-bonus-category purchases. With the Discover More, however, you'll only qualify for the 1% base rate when your total annual purchases exceed $3,000. Prior to that, all your non-bonus-category purchases will earn 0.25% back, a staggering 75% lower than the industry standard. Yikes!

Some programs not only have spending minimums, they also have reward maximums—like 5% back on up to only the first $1,500 in purchases.

The bottom line is to make sure you know all of your credit cards' rewards program details—the fine print and requirements for you to get the most rewards and then use your cards accordingly.